This invention relates to the manufacture of flexible collapsible tubes for packaging cosmetics and toiletry products such as lotions, toothpaste, etc. Such tubes are generally cylindrical, having a shoulder terminating in a threaded end adapted to receive a closure. The other end remains open for filling and is subsequently closed by heat sealing or other means. More specifically, this invention relates to a method and apparatus for manufacturing seamless, integral tubular containers by electrostatic deposition of a powder on a mold and subsequent sintering of the powder into a fused homogeneous mass.
In the past, the commercial manufacture of such tubes has been accomplished by injection molding, or by the extrusion of a tubular parison with subsequent welding of a shoulder and threaded neck portion to the extruded parison. With respect to the manufacture of these containers by injection molding, such requires large capital expenditures including investment in expensive two-piece molds, presses, and an extruder for the polymeric material. On the other hand, where tubular parisons are made, such requires an extruder to provide a cylindrical tube of polymeric material which is subsequent cooled and cut into the desired lengths. After the cylindrical tubes have been cooled, they are welded in some fashion to a shoulder and neck portion which is adapted to receive a closure, the shoulder and neck portion being previously formed by injection molding. Both of these processes are expensive, require the employment of additional undesirable manufacturing steps and do not permit a higher rate of production which is desirable.